A thermoelectric conversion element is capable of converting heat into electric power or converting electric power into heat. A thermoelectric conversion element formed of thermoelectric materials that exhibit the Seebeck effect can obtain thermal energy from a heat source having a relatively low temperature (that is, for example, equal to or lower than 200° C.) for conversion into electric power. Thermoelectric generation technology utilizing such a thermoelectric conversion element can, for example, make it possible to recover and effectively use unused thermal energy that has conventionally been discarded in the form of, for example, steam, hot water, or exhaust gas into an ambient environment.
A thermoelectric conversion device generally has such a so-called “π-shaped structure” that a p-type thermoelectric conversion element and an n-type thermoelectric conversion element form a pair with their carriers having different electrical polarities. This structure is disclosed, for example, in NPL 1. The p-type thermoelectric conversion element and the n-type thermoelectric conversion element of the thermoelectric conversion device having the “π-shaped structure” are electrically connected in series and are thermally connected in parallel. In this specification, the p-type and n-type thermoelectric conversion elements forming the pair are referred to as “thermoelectric conversion element pair”. A plurality of the thermoelectric conversion element pairs are electrically connected in series to compose a thermoelectric conversion module. The thermoelectric conversion module includes, for example, several tens of thermoelectric conversion element pairs. By converting thermal energy into electric power, the thermoelectric conversion module provides, for example, a voltage ranging from several millivolts to several volts.